The first step is to figure out how many days are in your average cycle. (It’s totally normal for your cycle to be a few days shorter or longer from month to month. That’s why we’re talking average cycle.
To calculate your period, you’ll need to count the days in between your last few periods. (Be sure to mark the days in your calendar so that you remember which day your period started each month. You can just use a star or a big letter ‘P’ if you don’t want other people knowing when you got your period.)
Start counting on the first day of your period and stop counting on the day before your next period. This is the number of days in one menstrual cycle. Do this for a few cycles. Add up the total number of days and then divide them by the number of cycles. That will give you the average number of days in your menstrual cycle. Once you know how many days are in your cycle, it’s super easy to track your period.
